chore(associations/scope): fix a few failing tests

lib/associations/has-many.js

@@ -19,7 +19,7 @@ module.exports = (function() {
     this.source = source;
     this.target = target;
     this.targetAssociation = null;
-    this.options = options;
+    this.options = options || {};
     this.sequelize = source.daoFactoryManager.sequelize;
     this.through = options.through;
     this.scope = options.scope;
@@ -106,9 +106,9 @@ module.exports = (function() {
           // If through is not default, determine pairing by through value (model/string)
           else {
             paired = self.options.through === association.options.through ||
-                     self.options.through === association.options.through.model ||
-                     self.options.through.model === association.options.through.model ||
-                     self.options.through.model === association.options.through;
+                     self.options.through === (association.options.through && association.options.through.model) ||
+                     (self.options.through && self.options.through.model) === (association.options.through && association.options.through.model) ||
+                     (self.options.through && self.options.through.model) === association.options.through;
           }
           // If paired, set properties identifying both associations as double linked, and allow them to each eachtoerh
           if (paired) {

lib/dialects/abstract/query-generator.js

@@ -536,7 +536,7 @@ module.exports = (function() {
 
           // check if model provided is through table
           var association;
-          if (!as && parentAssociation && parentAssociation.through === model) {
+          if (!as && parentAssociation && parentAssociation.through.model === model) {
             association = {as: Utils.singularize(model.tableName, model.options.language)};
           } else {
             // find applicable association for linking parent to this model